import java.util.*;

public class Q3
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        int x = in.nextInt();
        int y = 0;
        do
        {
          y += x;
        }while (x >= 50 && x <= 100);

        System.out.println(y);
    }
}